Page 1489 - Clinical Small Animal Internal Medicine

162 Autoimmune and Immune‐Mediated Skin Diseases 1427

diagnostic value. Histopathology reveals interface vacu- Initial lesions develop on haired skin and include ery-
VetBooks.ir olation and basal cell apoptosis. thematous macules and patches that progress to turgid
Clinical differential diagnoses include severe erythema
vesicles. The lesions evolve to ulcers and crusts. Lesions
multiforme, systemic lupus erythematosus, pemphigus
spared and mucosa is less frequently affected than in
vulgaris, severe dermatomyositis, and bullous pemphigoid. are not pruritic but can be painful. Pawpads are generally
Treatment involves immunosuppression using gluco- mucous membrane pemphigoid.
corticoids combined with azathioprine or ciclosporin. Diagnosis is based on the dermatohistopathologic
Pentoxifylline, vitamin E, topical glucocorticoids, or findings of skin biopsy and immunofluorescence or
hydroxychloroquine can be used as adjunctive therapy immunohistochemistry. Refer to the subepidermal
(see Table 162.1). Sun avoidance is potentially important blistering diseases introduction for details about biopsy
because sun exposure may be part of the disease patho- technique and special testing. Histopathology reveals
genesis. Topical and/or oral antibiotics along with general subepidermal bullae.
wound care should also be instituted. Complications may Clinical differential diagnoses include EBA (although
include secondary pyoderma and even septicemia. EBA typically features footpad involvement), pemphigus
Prognosis is generally good. variants, VCLE, and mucous membrane pemphigoid.
The presence of nonmucosal involvement is more
suggestive of BP than mucous membrane pemphigoid.
Autoimmune Subepidermal Treatment involves topical glucocorticoids, oral gluco-
Blistering Diseases corticoids, tetracycline with niacinamide, and/or azathio-
prine (see Table 162.1). Complications include pyoderma.
This group of diseases is autoimmune in nature and charac- Spontaneous remission has been reported although it
terized by vesicle formation on various parts of the body. The should be anticipated that life‐long therapy could be
diagnosis is based on signalment, physical examination, his- necessary.
topathology, and response to therapy. Immunohistochemistry
or immunofluorescence is also sometimes required to Epidermolysis Bullosa Acquisita
differentiate among the blistering diseases.
Bulla or vesicles should be sampled via wedge biopsy Epidermolysis bullosa acquisita is an autoimmune vesic-
for diagnostic purposes. If only erosions and ulcers are ulobullous disease that affects mostly young adult dogs.
present, the clinician should obtain a wedge biopsy Great Danes and male dogs are overrepresented.
encompassing both margins of an erosive lesion. It is Initial lesions include patchy erythema and vesicles of
important to include epidermis in the sample. A biopsy the face, oral cavity, concave pinna, axilla, and groin
that includes only dermis (e.g., center of an erosion or (Figure 162.5).
ulcer) will yield minimal diagnostic information. Samples Vesicles may be hemorrhagic. Areas of friction tend to
should be submitted to an experienced dermatohisto- have the most obvious lesions. The groin and axilla
pathologist to increase the chances of obtaining a defini- develop erosions quickly. The oral mucosa and footpads
tive diagnosis. Response to therapy and lesion appearance usually feature extensive sloughing. Affected individuals
can also guide the diagnosis. Bullous pemphigoid and
mucous membrane pemphigoid are fairly glucocorticoid
responsive, while epidermolysis bullosa acquisita (EBA)
is more glucocorticoid resistant.
The mucous membranes are predominantly affected
in mucous membrane pemphigoid. Areas of friction and
trauma (i.e., footpads) are predominantly affected in
EBA. Vesicular cutaneous lupus erythematosus (dis-
cussed above) features extensive abdominal erosions.
Bullous pemphigoid and EBA generally feature tense
vesicles, while the vesicles of vesicular cutaneous lupus
erythematosus are more flaccid.

Bullous Pemphigoid
Bullous pemphigoid (BP) is an autoimmune vesiculobul- Figure 162.5 One‐year‐old Great Dane with epidermolysis bullosa
lous disease that more often affects middle‐aged dogs. acquisita. Note the ulcers on the buccal mucosa and vesiculation
Breed and sex predilections have not been identified. at the lower lip margin. Source: Courtesy of Sandra Koch.